Classical trajectory calculations for the collisional energy transfer between vibrationally excited SO2 molecules and thermal Ar and He atoms are analyzed with respect to a partitioning of the total energy transfer between the "rotational" and "vibrational" components. It is shown that for the case studied (total energy of SO2 being 10 kcal/mol), "vibrational" energy transfer is governed by energy transfer to the active rotation. Therefore, the active rotation represents a gateway for vibrational energy transfer provided that during the time between successive collisions the intramolecular vibrational relaxation ensures microcanonical equipartitioning of the molecular energy. A comparison with previous trajectory calculations (Schranz, H. W.; Tree, J, J. Phys. Chem. 1986, 90, 6168) on the same system indicates that, at higher total energies of SO2, direct vibrational deactivation becomes more effective than the transfer via the rotational gateway.